http://www.pcgamer.com/warframes-plains-of-eidolon-expansion-launches-today/

Today, something a bit different is coming to Digital Extremes’ multiplayer action romp, Warframe. The Plains of Eidolon expansion is, for the first time, introducing an open-world area, the titular plains. It’s about nine square kilometers in size, and is full of secret caves, enemy camps and new missions. 

Along with this large new area, expect new gear, a new warframe, and a brand new mission type that will see you making some fancy weaponry. And you can’t have an open world without some relaxing diversions, so of course there’s fishing, and if you prefer to crack rocks instead of catching fish, there’s always mining.